1. The problem statement, all variables and given/known data We have y' = y^(1/3) with initial condition y(0)=0 It's stated that the partial derivative ∂f/∂y does not exist at y=0. Can anyone explain to me why this is? I don't understand how you can take the partial derivative if its not in the form f(x, y); there is no x. 2. Relevant equations Solving for y we have y = ((2/3)[t+c])^(3/2) if c=o, the initial condition is satisfied 3. The attempt at a solution help!